The purposes of the Data and Clinical Prediction Core and twofold. First, the Core will centralize recruitment, baseline data collection, data management and statistical consultation for clinical projects in the PERC. Second, efficient analysis of data collected by the Core will allow the development of the first multivariate clinical prediction rule to predict the occurrence of preeclampsia. Until now, limited success has been achieved using individual tests proposed to distinguish women who will develop preeclampsia from those who will not. The Core will recruit an estimated 550 eligible women per year from Magee Womens Hospital for whom baseline clinical, anthropometric, and laboratory data will be obtained. Longitudinal clinical data and biologic samples will also be collected and stored. Data will be organized and maintained using expertise within the Department of Epidemiology. Statistical consultation will be ongoing. The Clinical Prediction study will be a nested case-control design. One hundred ten preeclamptic patients will be compared to 220 non-preeclamptic, controls in formulating the rule; 60 cases will be compared to 120 controls in validating the rule. All formulation subjects will have been enrolled in the Core's longitudinal follow-up activities. To be included as cases, women must meet a rigorous case definition as reviewed by a panel of experts. Potential predictors that will be analyzed include baseline interview data, weight, body fatness, and laboratory tests. The clinical and test findings of cases and controls will be compared in order to identify women at high risk for the development of preeclampsia. From univariate tests and multivariate logistic regression models, prediction capabilities will be evaluated using Receiver Operating Curves; the simplified rule with the best test characteristics will be identified. Preeclampsia is a major contributor to maternal and perinatal morbidity and mortality. Prevention of this disease requires both an understanding of pathophysiology as well as a clinical characterization of women fated to develop the disease. The Core will assist in both pursuits.